In the related art, as a starter used to start an automobile, a jump-in type starter configured to jump a pinion gear toward a ring gear to be meshed with the ring gear upon starting an engine and drive the ring gear by the pinion gear to start the engine is known (for example, see Patent Literature 1).
In addition, in recent years, in order to increase silence or fuel efficiency of a vehicle, vehicles having a so-called idle stop function of switching an engine to be turned off when the vehicles are temporarily stopped have increased.
A starter disclosed in Patent Literature 1 is configured to be applied to the vehicle having the above-mentioned idle stop function. In the starter disclosed in Patent Literature 1, a drive shaft (an output shaft) is connected to a rotor shaft of a starting motor via a planetary gear type reduction gear. The drive shaft has both end sides in an axial direction, which are rotatably axially supported by a housing of the starter. A needle configured to advance and retreat via a lever (a gear plunger) by a magnet switch (an electromagnetic device) in the axial direction is spline-engaged with the drive shaft. In addition, a pinion gear configured to freely advance and retreat with respect to a ring gear in the axial direction is installed at the drive shaft, and is connected to the needle via a one-way clutch (a clutch mechanism).
Upon starting the engine, the pinion gear is jumped toward the ring gear to be meshed with the ring gear by the magnet switch via the lever, the needle and the one-way clutch, and rotation of the motor unit is transmitted to the pinion gear via a speed reduction mechanism to drive the ring gear. The ring gear and the pinion gear are configured of helical teeth (helical gears). A torsion direction of the teeth of the ring gear and the pinion gear is set such that a thrust load in a jump-in direction is applied to the pinion gear in a state in which the pinion gear drives the ring gear.
According to Patent Literature 1, when the pinion gear is meshed with the ring gear, the pinion gear receives a thrust load generated by a helix angle of the teeth of both gears to naturally advance in the jump-in direction. For this reason, a meshing property of the pinion gear with respect to the ring gear is improved.
However, components of the starter of a clutch mechanism, a pinion gear, and so on, have dimensional errors upon manufacture. For this reason, in the above-mentioned starter, when the pinion gear is meshed with the ring gear upon starting the engine, an aperture is generated between a point of action of the electromagnetic device and the clutch mechanism.
Here, when the lever (the gear plunger) is set to be attracted to a maximum attraction position and held by the magnet switch (the electromagnetic device), if no aperture is provided, in the case in which the lever is shaken in a direction in which a dimensional error of a part is large due to the error, the lever (the gear plunger) may not be attracted to the maximum attraction position and held. The above-mentioned aperture is generated by setting the dimension of each part through addition of the error upon design.
In a starter of Patent Literature 2, a second plunger unit is disposed to advance and retreat in an axial direction by a magnet switch (an electromagnetic device) concentrically with a drive shaft (an output shaft). A pinion gear is installed at the drive shaft to advance and retreat with respect to a ring gear in an axial direction.